The online retailer's option is currently available in Seattle, New York City, Philadelphia, Boston, Washington D.C., Baltimore, and Las Vegas. Should the service prove popular, it's a safe bet that Amazon will expand the program, although it's questionable whether the service would ever be logistically feasible on a nationwide level. Same-day delivery for residents in isolated rural towns seems unlikely.

As you'd expect, ultra-rush delivery isn't cheap. Amazon's Local Express shipping fees, which include "per shipment" and "per item" costs, aren't for the tightfisted. Example: Same-day delivery of a cell phone runs about $21 ($16.99 per shipment + $3.99 per item). However, Amazon Prime members, who pay $79 a year for free shipping, get Local Express delivery for $5.99.

Local Express is reminiscent of , a free online delivery service from the dot-com era that flamed out in 2001. Kozmo, using an army of deliverers on bikes, scooters, and vans, brought small goods such as videos and candy bars within an hour to your door. But like so many other calculator-challenged startups back then, Kozmo bled money and soon went belly-up.

Amazon, of course, is too savvy and experienced to duplicate Kozmo's mistakes, and Local Express Delivery is designed to generate profits for the retailer. Who'll use it? Most likely 1) hopeless procrastinators desperate to meet a birthday or holiday deadline; and 2) spendthrifts, wastrels, squanderers, and other compulsive shoppers.

Same-day shipping also eliminates (well, almost) one of the drawbacks of online shopping: no instant gratification. Instead of waiting a day or more to get a package, you'll get it the same day. While that can't quite match the sensation of bringing an item home from the store, it's pretty darn close.